new plugin check_connections.sh

Add new plugin that check the number of connections/sockets in a given state

check_connections.sh

@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+
+# Nagios Exit Codes
+OK=0
+WARNING=1
+CRITICAL=2
+UNKNOWN=3
+
+usage()
+{
+cat <<EOF
+
+Check the number of connections/sockets in a given state.
+Uses iproute2's ss tool to retrieve connections.
+
+     Options:
+        -s         State of connection (def: all)
+		   (established, syn-sent, syn-recv, fin-wait-1, fin-wait-2, time-wait,
+			closed, close-wait, last-ack, listen, and closing)
+	-f 	   Apply quoted ss expression filter e.g. '( dst 192.168.1/24 and dport >= :1024 )'
+	-p <type>  Set protocol or family type (udp/tcp/inet/inet6)
+        -c         Critical threshold as an integer
+        -w         Warning threshold as an integer
+
+Usage: $0 -s established '( sport = :443 )' -w 800 -c 1000
+EOF
+}
+
+argcheck() {
+# if less than n argument
+if [ $ARGC -lt $1 ]; then
+        echo "Missing arguments! Use \`\`-h'' for help."
+        exit 1
+fi
+}
+
+if ! command -v ss >/dev/null 2>&1; then
+	echo -e "ERROR: ss is not installed or not found in \$PATH!"
+	exit 1
+fi
+
+# Define now to prevent expected number errors
+STATE=all
+CRIT=0
+WARN=0
+COUNT=0
+ARGC=$#
+CHECK=0
+
+argcheck 1 
+
+while getopts "hc:s:f:p:w:" OPTION
+do
+     case $OPTION in
+         h)
+	     usage
+             ;;
+         s)
+             STATE="$OPTARG"
+	     CHECK=1
+             ;;
+         f)
+ 	     FILTER="$OPTARG"
+	     CHECK=1
+             ;;
+	 p)
+	     if [[ $OPTARG == tcp ]]; then
+                PROTOCOL="-t"
+             elif [[ $OPTARG == udp ]]; then
+                PROTOCOL="-u"
+             elif [[ $OPTARG == inet ]]; then
+                PROTOCOL="-4"
+             elif [[ $OPTARG == inet6 ]]; then
+                PROTOCOL="-6"
+             else
+                echo "Error: Protocol or family type no valid!"
+		exit 1
+             fi
+	     CHECK=1
+	     ;; 
+         c)
+	     CRIT="$OPTARG"
+	     CHECK=1
+             ;;
+	 w) 
+	     WARN="$OPTARG"
+	     CHECK=1
+	     ;;
+         \?)
+             exit 1
+             ;;
+     esac
+done
+
+COUNT=$(ss -n state $STATE $PROTOCOL $FILTER | grep -v 'State\|-Q' | wc -l)
+
+if [ $COUNT -gt $CRIT ]; then
+        echo "$COUNT sockets in $STATE state!"
+        exit $CRITICAL
+elif [ $COUNT -gt $WARN ]; then
+        echo "$COUNT sockets in $STATE state!"
+        exit $WARNING
+else
+        echo "$COUNT sockets in $STATE state."
+        exit $OK
+fi